New antibiotic a 'game changer'

A turning point in the war against superbugs may have been reached with the discovery of a potent new antibiotic that shows no sign of inducing drug resistance.

The drug, named teixobactin, was isolated from soil bacteria using a revolutionary technique that may in future yield a rich harvest of previously hidden antibiotic compounds.

It has the ability to kill many types of harmful bacteria, including the superbug MRSA (methicillin resistant Staphylococcus aureus), by breaking down their cell walls.

Because it targets fatty molecules in the cell wall instead of proteins it is also much less likely than most antibiotics to induce microbial resistance.

In tests, US scientists found no evidence of bugs evolving ways to cheat death by teixobactin, which proved harmless to mammalian cells.

Professor Kim Lewis, from Northeastern University in Boston, who led the US team, said the discovery was exciting.

"No resistance normally means that we discovered a new detergent, which is a molecule that will destroy the membrane of the bacterial cell but also will destroy the membranes of our cells, so these are toxic compounds," Lewis said.

"That was my first reaction; that we found another boring molecule. But then in parallel we tested that compound against mammalian cells, and found it was not toxic against mammalian cells.

"So we have something very intriguing. Here is a new molecule that hits bacterial cells, does not hit mammalian cells, and there's no resistance ... That was unique and very exciting."

Teixobactin is effective against some microbes - known as "gram positive" bacteria - and not others.

But the organisms vulnerable to it include some very nasty examples, such as MRSA, the TB bug mycobacterium tuberculosis, and Clostridium difficile (C. diff).

The drug will not work against "gram negative" bacteria such as Escherichia coli (E.coli) which have a kind of molecular armour plating protecting their cell membranes.

However, the research goes much further than identifying one promising new drug.

It potentially opens the door to further discoveries that could boost the world's antibiotic arsenal and turn the tide against the superbugs.

Most antibiotics are derived from soil bacteria and fungi, which use them as weapons in an ongoing battle for survival with other micro-organisms.

But many remain hidden from science, because 99 per cent of the simple life forms producing them refuse to grow in laboratory Petri dishes.

This makes them difficult to study and screen for new products.

Lewis and his team tried a new tack by growing bacteria in the place they know best, the soil.

Diluted soil samples containing the bugs were placed in culture wells sandwiched between two semi-permeable membranes and buried in earth.

Speaking on a podcast issued by the journal Nature, which published the research, the professor said scientists obtained 50,000 isolates from 10,000 soil bacteria strains, from which they identified 25 new antibiotics including teixobactin.